Which repeating units are present in chromatin?

Which of the following statements is/are correct?
$(a)$ The nuclear matrix or nucleoplasm contains the nucleolus and chromatin.
$(b)$ The outer nuclear membrane $(Ectokaryotheca)$ is usually continuous with the endoplasmic reticulum and also bears ribosomes on it.
$(c)$ Cells that are actively synthesizing protein have small and fewer nucleoli.

$A$ chromosome having a sub-terminal centromere is called:

The shape of chromosomes can be identified by which of the following?

$DNA$ is primarily found in:

Chromatin found in the nucleus was discovered by